Rokugan

In Rokugan, also known as the Emerald Empire, all land is owned by The Emperor. The territory given to the respective clans and daimyo is given by the Emperor for the daimyo to act as stewards, not as owners, over their respective provinces. In return for for permission to live on the Emperor's land, the clans pay taxes to the Emperor.

Should the Emperor believe that a clan cannot protect the lands that they hold for him, he can turn stewardship over to another clan. This is how many of the wars in Rokugan begin, one clan proving to the Emperor that another clan cannot sufficiently protect their land.